Plastic Formwork have started to gain popularity at recent
times because it has many advantages and a few disadvantages too. Because of
environmental protection issues, ability of recycling, corrosion and waterproof
resistance, plastic formwork have started to get popularity. There are ways to
decrease the disadvantages of plastic formwork which we are going to mention.
Advantages of Plastic Formworks
- Lightweight: Plastic Formworks are lightweight in comparison
to steel and wooden formwork. It is easy to lay and transport.
- Rust Resistance: If we use steel formwork, it will slowly
develop rust. But plastic never develops rust.
- Water Resistance: Steel and wooden formwork will get wear
and tear over time because of rain water. But plastic formwork is water
resistant and will be unaffected
- Reusablility: Plastic Formwork is more reusable than wooden
and iron framework.
- Easy to demould: Concrete doesn’t stick in plastic formwork
unlike in steel and wooden formwork where we need to dust off the concrete from
the formwork surface after curing of concrete for enough time. Therefore, cleaning is not required in plastic formwork
and it will be easy to demould.
- Reduction of Costs: The number of turnover is large as
compared to wooden and steel. As plastic framework lasts for a large number of
time, it’s cost will be very low in the long run.
- Ability to Recycle: Plastic Formworks are industry made. So
they are completely recyclable. Steel and wooden formwork are subjected to
wear, dust and rust and are not completely reusable.
- Easy to work into new shape and size: As plastic formworks
are lighter, they are easy to cut into various pieces and shapes during
formwork installation and maintenance.
- No need to apply oil: As plastic formwork does not stick
with concrete, there is no need to apply oil to the formwork unlike in steel
and wooden formwork.
- Ease of installation: The first reason that plastic formwork
is easy to install is that it is lightweight. Auto level of plugging system
will make it smooth to install and time of completion is very less and will
require lesser manpower.
Disadvantages of Plastic Formwork
Though the plastic formwork has a lot of advantages, it also
has got some disadvantages too. And the issue is major and that’s why, plastic
formwork has a lot of development and research going on to make it more usable
and completely replace steel and wooden formwork. The following are the disadvantages of Plastic Formwork.
Low Rigidity and Strength
The bending stress and bending elastic modulus of plastic is
very less as compared to steel and wood. That’s why it is only usable for slab
casting with lesser thickness.
Low Bearing Capacity of Plastic Formwork
Plastic formwork is used only in cases where roof is
required to be casted and low bearing capacity can suffice the requirement. But
plastic formwork cannot be used in wall and column casting because the pressure involved in the formwork in column casting is larger than slab casting.
Coefficient of Thermal contraction and Expansion of plastic is large
The coefficient of Thermal contraction and expansion is
larger, resulting in higher expansion when there is high temperature. Plastic
tend to make larger gaps in between the joints, resulting in the leakage of
concrete. This problem has a unique solution to it, but is still considered a
problem and is a subject of research.
Problem of thermal expansion and contraction can be solved
by placing foams between two formworks that will prevent the leakage between
the joints of plastic formwork.
Fear of being burnt from welding
This problem occurs when the reinforcement bars are required
to be welded instead of connecting with wires. The flakes will touch the
plastic formwork and make it burn. Anti-flaming agents could be used in
manufacturing plastic formwork, but the plastic formwork is never completely
resistant against flame.